Osthole shows the potential to overcome P-glycoprotein‑mediated multidrug resistance in human myelogenous leukemia K562/ADM cells by inhibiting the PI3K/Akt signaling pathway

Panax notoginseng saponins reverse steroid resistance in lupus nephritis: Involvement of the suppression of exosomal P-gp levels from lymphocytes to glomerular endothelial cells

Microangiopathy is the most basic pathological manifestation of lupus nephritis (LN), and glomerular endothelial cells (GECs) injury is an important pathological mechanism. LN patients with microangiopathy are prone to steroid resistance (SR). Our previous studies confirmed that Panax notoginseng saponins (PNS) could reverse SR by downregulating the expression of P-gp in SR lymphocytes of LN mice (SLCsL/S). However, the mechanism of how circulating lymphocytes transmit SR information to GECs and thus affect the efficacy of kidney treatment is not clear. Recent studies have found that exosomes (exos) are an important carrier for intercellular bioactive substance communication. But whether exosomes derived from SLCsL/S mediate SR in GECs and PNS interventions. To solve this problem, Exosomes isolated from SLCsL/S were characterized, and in vitro cell coculture was further conducted to investigate the effect of SLCsL/S-derived exosomes in the SR of GECs and PNS intervention. Sequencing was used to define the exosomal miRNA expression profiling of SR GECs. Moreover, the in vivo experiments were performed through the injection of exosomes extracted from SLCsL/S into the tail vein of mice. Our research results indicate that exosomes derived from SLCsL/S could transmit SR information to GECs and lead to the aggravation of inflammatory injury through conferring P-gp, which were negated by a P-gp inhibitor. Further, we identified higher levels of exosomal miR-125b-5p from SR GECs were associated with SR in LN and could serve as biomarker for the risk of developing SR. PNS could reverse the SR of GECs and alleviate inflammatory injury by suppressing exosomal P-gp levels from lymphocytes to GECs in vitro and in vivo. However, the specific molecular mechanism by which PNS regulates exosomes has not yet been elucidated, and we need to conduct more in-depth research in the future. Overall, Our findings suggest that exosomal transfer of SLCsL/S derived P-gp confer SR to GECs, and PNS can target exosome communication to reverse SR in LN, which provides new ideas and a scientific basis for improving the clinical efficacy of traditional Chinese medicine in the treatment of refractory LN.

Targeting MAGI2-AS3-modulated Akt-dependent ATP-binding cassette transporters as a possible strategy to reverse temozolomide resistance in temozolomide-resistant glioblastoma cells

Drug resistance is a major impediment to the successful treatment of glioma. This study aimed to elucidate the effects and mechanisms of the long noncoding RNA membrane-associated guanylate kinase inverted-2 antisense RNA 3 (MAGI2-AS3) on temozolomide (TMZ) resistance in glioma cells. MAGI2-AS3 expression in TMZ-resistant glioblastoma (GBM) cells was analyzed using the Gene Expression Omnibus data set GSE113510 and quantitative real-time PCR (qRT-PCR). Cell viability and TMZ half-maximal inhibitory concentration values were determined using the MTT assay. Apoptosis and cell cycle distribution were evaluated using flow cytometry. The expression of multidrug resistance 1 (MDR1), ATP-binding cassette superfamily G member 2 (ABCG2), protein kinase B (Akt), and phosphorylated Akt was detected using qRT-PCR and/or western blot analysis. MAGI2-AS3 was expressed at low levels in TMZ-resistant GBM cells relative to that in their parental cells. MAGI2-AS3 re-expression alleviated TMZ resistance in TMZ-resistant GBM cells. MAGI2-AS3 overexpression also accelerated TMZ-induced apoptosis and G2/M phase arrest. Mechanistically, MAGI2-AS3 overexpression reduced MDR1 and ABCG2 expression and inhibited the Akt pathway, whereas Akt overexpression abrogated the reduction in MDR1 and ABCG2 expression induced by MAGI2-AS3. Moreover, activation of the Akt pathway inhibited the effects of MAGI2-AS3 on TMZ resistance. MAGI2-AS3 inhibited tumor growth and enhanced the suppressive effect of TMZ on glioma tumorigenesis in vivo. In conclusion, MAGI2-AS3 reverses TMZ resistance in glioma cells by inactivating the Akt pathway.

Development of Polymersomes Co-Delivering Doxorubicin and Melittin to Overcome Multidrug Resistance

Multidrug resistance (MDR) is one of the major barriers in chemotherapy. It is often related to the overexpression of efflux receptors such as P-glycoprotein (P-gp). Overexpressed efflux receptors inhibit chemotherapeutic efficacy by pumping out intracellularly delivered anticancer drugs. In P-gp-mediated MDR-related pathways, PI3K/Akt and NF-kB pathways are commonly activated signaling pathways, but these pathways are downregulated by melittin, a main component of bee venom. In this study, a polymersome based on a poly (lactic acid) (PLA)-hyaluronic acid (HA) (20k-10k) di-block copolymer and encapsulating melittin and doxorubicin was developed to overcome anticancer resistance and enhance chemotherapeutic efficacy. Through the simultaneous delivery of doxorubicin and melittin, PI3K/Akt and NF-κB pathways could be effectively inhibited, thereby downregulating P-gp and successfully enhancing chemotherapeutic efficacy. In conclusion, a polymersome carrying an anticancer drug and melittin could overcome MDR by regulating P-gp overexpression pathways.

P-glycoprotein: new insights into structure, physiological function, regulation and alterations in disease

The multidrug resistance phenomenon presents a major threat to the pharmaceutical industry. This resistance is a common occurrence in several diseases and is mediated by multidrug transporters that actively pump substances out of the cell and away from their target regions. The most well-known multidrug transporter is the P-glycoprotein transporter. The binding sites within P-glycoprotein can accommodate a variety of compounds with diverse structures. Hence, numerous drugs are P-glycoprotein substrates, with new ones being identified every day. For many years, the mechanisms of action of P-glycoprotein have been shrouded in mystery, and scientists have only recently been able to elucidate certain structural and functional aspects of this protein. Although P-glycoprotein is highly implicated in multidrug resistant diseases, this transporter also performs various physiological roles in the human body and is expressed in several tissues, including the brain, kidneys, liver, gastrointestinal tract, testis, and placenta. The expression levels of P-glycoprotein are regulated by different enzymes, inflammatory mediators and transcription factors; alterations in which can result in the generation of a disease phenotype. This review details the discovery, the recently proposed structure and the regulatory functions of P-glycoprotein, as well as the crucial role it plays in health and disease.

The Mechanism of Osthole in the Treatment of Gastric Cancer Based on Network Pharmacology and Molecular Docking Technology

Objective

To study the mechanism of osthole in GC based on network pharmacology and molecular docking.

Methods

The potential targets of osthole were predicted through the TCM System Pharmacology Analysis Platform, SwissTargetPrediction, and PharmMapper database. Targets related to gastric cancer were obtained through OMIM and GeneCard database. The online tool Venny 2.1.0 was used to screen GC and common target of osthole. The targets after the intersection of drugs and diseases were entered into the STRING database, and the protein interaction network was constructed, and the core targets with high correlation were screened out. The WebGestalt website was used to GO functional enrichment and KEGG pathway analysis and visualization with KOBAS website. The Cytoscape 3.8.2 was employed to draw the C-T-P-D (compound-target-pathway-disease) network visualization diagram. Finally, molecular docking validation was performed using PyMOL 2.5 and Discovery Studio Standalone.

Results

Through prediction and screening, 108 corresponding targets were screened from osthole, and 173 targets were obtained after intersecting with gastric cancer targets. Among them, the top ten targets were the core targets of this study, including MAPK3, MAPK1, SRC, AKT1, HSP90AA1, RXRA, ESR1, RELA, MAPK14, and EGFR. The analysis of GO, KEGG, and PPI showed that the mechanism of action of osthole against GC may be closely related to the regulation of the PI3K signaling pathway. The results of molecular docking showed that osthole had a good affinity with MAPK3, which is a crucial part of the PI3K signaling pathway.

Conclusion

This study preliminarily revealed the targets and related pathways of osthole in the treatment of gastric cancer and provided a new idea for further exploration of osthole targeted prevention and treatment of gastric cancer.

An engineered abcb4 expression model reveals the central role of NF-κB in the regulation of drug resistance in zebrafish

Multi-drug resistance (MDR) is a phenomenon that tumor cells are exposed to a chemotherapeutic drug for a long time and then develop resistance to a variety of other anticancer drugs with different structures and different mechanisms. The in vitro studies of tumor cell lines cannot systematically reflect the role of MDR gene in vivo, and the cost of in vivo studies of transgenic mice as animal models is high. Given the myriad merits of zebrafish relative to other animal models, we aimed to establish a screening system using zebrafish stably expressing ATP-binding cassette (ATP-cassette) superfamily transporters and unveil the potential regulatory mechanism. We first used the Tol2-mediated approach to construct a Tg (abcb4:EGFP) transgenic zebrafish line with ATP-binding cassette (ABC) subfamily B member 4 (abcb4) gene promoter to drive EGFP expression. The expression levels of abcb4 and EGFP were significantly increased when Tg(abcb4:EGFP) transgenic zebrafish embryos were exposed to doxorubicin (DOX) or vincristine (VCR), and the increases were accompanied by a marked decreased accumulation of rhodamine B (RhB) in embryos, indicating a remarkable increase in DOX or VCR efflux. Mechanistically, Akt and Erk signalings were activated upon the treatment with DOX or VCR. With the application of Akt and Erk inhibitors, drug resistance was reversed with differing responsive effects. Notably, downstream NF-κB played a central role in the regulation of abcb4-mediated drug resistance. Taken together, the data indicate that the engineered Tg(abcb4:EGFP) transgenic zebrafish model is a new platform for screening drug resistance in vivo, which may facilitate and accelerate the process of drug development.

Panax notoginseng saponins reverse P-gp-mediated steroid resistance in lupus: involvement in the suppression of the SIRT1/FoxO1/MDR1 signalling pathway in lymphocytes

Background

P-glycoprotein (P-gp)-mediated steroid resistance (SR) has been suggested to play a significant role in lupus nephritis (LN) treatment failure. Panax notoginseng saponins (PNS), the main effective components of the traditional Chinese medicine notoginseng, exhibited potent reversal capability of P-gp-mediated SR, but its mechanism remains unknown. This study aimed to investigate the effect of PNS on reversing SR in lupus and its underlying mechanism in vivo and in vitro.

Methods

In this study, an SR animal and splenic lymphocyte model were established using low-dose methylprednisolone (MP). Flow cytometry was used to detect the effect of PNS on reversing P-gp-mediated SR and the expression of P-gp in different T-cells phenotypes. Serum levels of ANA and dsDNA in lupus mice were measured by ELISA. Apoptosis was identified by Annexin V-FITC/PI staining. RT–PCR and Western blotting were used to detect the protein and mRNA expression levels of SIRT1, FoxO1, and MDR1 in SR splenic lymphocytes from lupus mice (SLCs/MPs).

Results

PNS could reverse the SR in lupus mice. Simultaneously, PNS increased the apoptotic effect of MP on SLCs/MP cells. The increased accumulation of rhodamine-123 (Rh-123) indicated that intracellular steroid accumulation could be increased by the action of PNS. Moreover, PNS decreased the expression of P-gp levels. Further experiments elucidated that the SIRT1/FoxO1/MDR1 signalling pathway existed in SLCs/MP cells, and PNS suppressed its expression level to reverse SR. The expression of P-gp in Th17 from SLCs/MP cells was increased, while PNS could reduce its level in a more obvious trend.

Conclusion

The present study suggested that PNS reversed P-gp-mediated SR via the SIRT1/FoxO1/MDR1 signalling pathway, which might become a valuable drug for the treatment of SR in lupus. Th17 might be the main effector cell of PNS reversing SR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03499-5.

Rhinacanthin-C enhances chemosensitivity of breast cancer cells via the downregulation of P-glycoprotein through inhibition of Akt/NF-kappa B signaling pathway

Introduction: High expression of P-glycoprotein (P-gp) has been linked to multidrug resistance (MDR) and chemotherapeutic failure. Previously, we demonstrated that rhinacanthin-C, a naphthoquinone from Rhinacanthus nasutus, was able to enhance the cytotoxicity of doxorubicin against breast cancer MCF-7 cells via direct P-gp inhibition. In this study, we looked at its effect on P-gp downregulation and the mechanism involved in the resistance of MCF-7 cells to doxorubicin. Methods: Doxorubicin-resistant MCF-7 (MCF-7/DOX) cells were exposed to rhinacanthin-C for 24-48 hours prior to the assessment of their chemosensitivity via MTT assay, P-gp activity via calcein-AM uptake assay, P-gp expression, and signaling via qRT-PCR and western blot analyses. Results: Pretreatment with 1 µM of rhinacanthin-C for 48 hours significantly enhanced cytotoxicity of doxorubicin, as well as camptothecin and etoposide, to MCF-7/DOX cells. In the rhinacanthin-C-treated cells, reduction of MDR1 mRNA and P-gp levels and increased intracellular calcein were observed. Moreover, phosphorylation of Akt, NF-ᴋB and IκB-α, along with YB-1 expression, significantly decreased after 24-hour treatment with rhinacanthin-C. In contrast, the naphthoquinone had no effect on expression levels of ERK1/2 and phosphorylated ERK1/2 under similar conditions. Conclusion: Rhinacanthin-C, at a non-cytotoxic concentration (1 µM), could downregulate P-gp expression in MCF-7/DOX cells via the inhibition of the Akt/NF-ᴋB signaling pathway and YB-1 expression. Long-term exposure to this natural naphthoquinone may increase the chemosensitivity of cancer cells with MDR phenotype.

Advances in understanding the role of P-gp in doxorubicin resistance: Molecular pathways, therapeutic strategies, and prospects

P-glycoprotein (P-gp) is a drug efflux transporter that triggers doxorubicin (DOX) resistance. In this review, we highlight the molecular avenues regulating P-gp, such as Nrf2, HIF-1α, miRNAs, and long noncoding (lnc)RNAs, to reveal their participation in DOX resistance. These antitumor compounds and genetic tools synergistically reduce P-gp expression. Furthermore, ATP depletion impairs P-gp activity to enhance the antitumor activity of DOX. Nanoarchitectures, including liposomes, micelles, polymeric nanoparticles (NPs), and solid lipid nanocarriers, have been developed for the co-delivery of DOX with anticancer compounds and genes enhancing DOX cytotoxicity. Surface modification of nanocarriers, for instance with hyaluronic acid (HA), can promote selectivity toward cancer cells. We discuss these aspects with a focus on P-gp expression and activity.

Apoptosis Deregulation and the Development of Cancer Multi-Drug Resistance

Simple Summary

Despite recent therapeutic advances against cancer, many patients do not respond well or respond poorly, to treatment and develop resistance to more than one anti-cancer drug, a term called multi-drug resistance (MDR). One of the main factors that contribute to MDR is the deregulation of apoptosis or programmed cell death. Herein, we describe the major apoptotic pathways and discuss how pro-apoptotic and anti-apoptotic proteins are modified in cancer cells to convey drug resistance. We also focus on our current understanding related to the interactions between survival and cell death pathways, as well as on mechanisms underlying the balance shift towards cancer cell growth and drug resistance. Moreover, we highlight the role of the tumor microenvironment components in blocking apoptosis in MDR tumors, and we discuss the significance and potential exploitation of epigenetic modifications for cancer treatment. Finally, we summarize the current and future therapeutic approaches for overcoming MDR.

Abstract

The ability of tumor cells to evade apoptosis is established as one of the hallmarks of cancer. The deregulation of apoptotic pathways conveys a survival advantage enabling cancer cells to develop multi-drug resistance (MDR), a complex tumor phenotype referring to concurrent resistance toward agents with different function and/or structure. Proteins implicated in the intrinsic pathway of apoptosis, including the Bcl-2 superfamily and Inhibitors of Apoptosis (IAP) family members, as well as their regulator, tumor suppressor p53, have been implicated in the development of MDR in many cancer types. The PI₃K/AKT pathway is pivotal in promoting survival and proliferation and is often overactive in MDR tumors. In addition, the tumor microenvironment, particularly factors secreted by cancer-associated fibroblasts, can inhibit apoptosis in cancer cells and reduce the effectiveness of different anti-cancer drugs. In this review, we describe the main alterations that occur in apoptosis-and related pathways to promote MDR. We also summarize the main therapeutic approaches against resistant tumors, including agents targeting Bcl-2 family members, small molecule inhibitors against IAPs or AKT and agents of natural origin that may be used as monotherapy or in combination with conventional therapeutics. Finally, we highlight the potential of therapeutic exploitation of epigenetic modifications to reverse the MDR phenotype.

Osthole: an overview of its sources, biological activities, and modification development

Osthole, also known as osthol, is a coumarin derivative found in several medicinal plants such as Cnidium monnieri and Angelica pubescens. It can be obtained via extraction and separation from plants or total synthesis. Plenty of experiments have suggested that osthole exhibited multiple biological activities covering antitumor, anti-inflammatory, neuroprotective, osteogenic, cardiovascular protective, antimicrobial, and antiparasitic activities. In addition, there has been some research done on the optimization and modification of osthole. This article summarizes the comprehensive information regarding the sources and modification progress of osthole. It also introduces the up-to-date biological activities of osthole, which could be of great value for its use in future research.

Anti-Cancer Effects of Zotarolimus Combined with 5-Fluorouracil Treatment in HCT-116 Colorectal Cancer-Bearing BALB/c Nude Mice

Zotarolimus is a semi-synthetic derivative of rapamycin and an inhibitor of mammalian target of rapamycin (mTOR) signaling. Currently, zotarolimus is used to prolong the survival time of organ grafts, but it is also a novel immunosuppressive agent with potent anti-proliferative activity. Here, we examine the anti-tumor effect of zotarolimus, alone and in combination with 5-fluorouracil, on HCT-116 colorectal adenocarcinoma cells implanted in BALB/c nude mice. Compared with the control mice, mice treated with zotarolimus or zotarolimus combined with 5-FU showed retarded tumor growth; increased tumor apoptosis through the enhanced expression of cleaved caspase 3 and extracellular signal-regulated kinase (ERK) phosphorylation; reduced inflammation-related factors such as IL-1β, TNF-α, and cyclooxygenase-2 (COX-2) protein; and inhibited metastasis-related factors such as CD44, epidermal growth factor receptor (EGFR), transforming growth factor β (TGF-β), and vascular endothelial growth factor (VEGF). Notably, mice treated with a combination of zotarolimus and 5-FU showed significantly retarded tumor growth, reduced tumor size, and increased tumor inhibition compared with mice treated with 5-FU or zotarolimus alone, indicating a strong synergistic effect. This in vivo study confirms that zotarolimus or zotarolimus combined with 5-FU can be used to retard colorectal adenocarcinoma growth and inhibit tumorigenesis. Our results suggest that zotarolimus may increase the chemo-sensitization of tumor cells. Therefore, zotarolimus alone and zotarolimus combined with 5-FU may be potential anti-tumor agents in the treatment of human colon adenocarcinoma. Future research on zotarolimus may lead to the development of new therapeutic strategies.

Phytochemicals reverse P-glycoprotein mediated multidrug resistance via signal transduction pathways

P-glycoprotein, encoded by ATP-binding cassette transporters B1 gene (ABCB1), renders multidrug resistance (MDR) during cancer chemotherapy. Several synthetic small molecule inhibitors affect P-glycoprotein (P-gp) transport function in MDR tumor cells. However, inhibition of P-gp transport function adversely accumulates chemotherapeutic drugs in non-target normal tissues. Moreover, most small-molecule P-gp inhibitors failed in the clinical trials due to the low therapeutic window at the maximum tolerated dose. Therefore, downregulation of ABCB1-gene expression (P-gp) in tumor tissues seems to be a novel approach rather than inhibiting its transport function for the reversal of multidrug resistance (MDR). Several plant-derived phytochemicals modulate various signal transduction pathways and inhibit translocation of transcription factors, thereby reverses P-gp mediated MDR in tumor cells. Therefore, phytochemicals may be considered an alternative to synthetic small molecule P-gp inhibitors for the reversal of MDR in cancer cells. This review discussed the role of natural phytochemicals that modulate ABCB1 expression through various signal transduction pathways in MDR cancer cells. Therefore, modulating the cell signaling pathways by phytochemicals might play crucial roles in modulating ABCB1 gene expression and the reversal of MDR.

Nanoplatform-based natural products co-delivery system to surmount cancer multidrug-resistant

The emergence of multidrug resistance (MDR) in malignant tumors is the primary reason for invalid chemotherapy. Antitumor drugs are often adversely affected by the MDR of tumor cells. Treatments using conventional drugs, which have specific drug targets, hardly regulate the complex signaling pathway of MDR cells because of the complex formation mechanism of MDR. However, natural products have positive advantages, such as high efficiency, low toxicity, and ability to target multiple mechanism pathways associated with MDR. Natural products, as MDR reversal agents, synergize with chemotherapeutics and enhance the sensitivity of tumor cells to chemotherapeutics, and the co-delivery of natural products and antitumor drugs with nanocarriers maximizes the synergistic effects against MDR in tumor cells. This review summarizes the molecular mechanisms of MDR, the advantages of natural products combined with chemotherapeutics in offsetting complicated MDR mechanisms, and the types and mechanisms of natural products that are potential MDR reversal modulators. Meanwhile, aiming at the low bioavailability of cocktail combined natural products and chemotherapeutic in vivo, the advantages of nanoplatform-based co-delivery system and recent research developments are illustrated on the basis of our previous research. Finally, prospective horizons are analyzed, which are expected to considerably improve the nano-co-delivery of natural products and chemotherapeutic systems for MDR reversal in cancer.

Control of Oxidative Stress in Cancer Chemoresistance: Spotlight on Nrf2 Role

Chemoresistance represents the main obstacle to cancer treatment with both conventional and targeted therapy. Beyond specific molecular alterations, which can lead to targeted therapy, metabolic remodeling, including the control of redox status, plays an important role in cancer cell survival following therapy. Although cancer cells generally have a high basal reactive oxygen species (ROS) level, which makes them more susceptible than normal cells to a further increase of ROS, chemoresistant cancer cells become highly adapted to intrinsic or drug-induced oxidative stress by upregulating their antioxidant systems. The antioxidant response is principally mediated by the transcription factor Nrf2, which has been considered the master regulator of antioxidant and cytoprotective genes. Nrf2 expression is often increased in several types of chemoresistant cancer cells, and its expression is mediated by diverse mechanisms. In addition to Nrf2, other transcription factors and transcriptional coactivators can participate to maintain the high antioxidant levels in chemo and radio-resistant cancer cells. The control of expression and function of these molecules has been recently deepened to identify which of these could be used as a new therapeutic target in the treatment of tumors resistant to conventional therapy. In this review, we report the more recent advances in the study of Nrf2 regulation in chemoresistant cancers and the role played by other transcription factors and transcriptional coactivators in the control of antioxidant responses in chemoresistant cancer cells.

Activation of PI3K/AKT/mTOR Pathway Causes Drug Resistance in Breast Cancer

Although chemotherapy, targeted therapy and endocrine therapy decrease rate of disease recurrence in most breast cancer patients, many patients exhibit acquired resistance. Hyperactivation of the PI3K/AKT/mTOR pathway is associated with drug resistance and cancer progression. Currently, a number of drugs targeting PI3K/AKT/mTOR are being investigated in clinical trials by combining them with standard therapies to overcome acquired resistance in breast cancer. In this review, we summarize the critical role of the PI3K/AKT/mTOR pathway in drug resistance, the development of PI3K/AKT/mTOR inhibitors, and strategies to overcome acquired resistance to standard therapies in breast cancer.

Investigation of a new oxazolidine derivative in human resistance acute leukemia cells: deciphering its mechanism of action by label-free proteomic

The present study aimed to evaluate the mechanism of action of the antineoplastic activity of an oxazolidine derivative, LPSF/NB-3 (5-(4-cloro-benzilideno)-3-etil-2-tioxo-oxazolidin-4-ona). Cytotoxicity assays were performed in peripheral blood mononuclear cells (PBMCs) and resistant acute leukemia cell line (HL-60/MX1) by the MTT method. LPSF/NB-3 exhibited cytotoxicity in HL-60/MX1, but it was not toxic to healthy cells in the highest dose tested (100 μM). The protein extract of HL-60/MX1 cells treated with LPSF/NB-3 was subjected to proteomic analysis using two-dimensional chromatography coupled to mass spectrometry. We could identify a total of 2652 proteins, in which 633 were statistically modulated. Within the group of protein considered for the quantitative analysis with the established criteria, 262 were differentially expressed, 146 with increased expression and 116 with decreased expression in the sample treated with LPSF/NB-3 compared to the control. The following differentially expressed pathways were found: involving regulation of the cytoskeleton, DNA damage, and transduce cellular signals. Networks that were highlighted are related to the immune system. The ELISA technique was used to assess the immunomodulatory potential of LPSF/NB-3 in PBMCs. We observed significant decrease of IFNγ (p < 0.01) and dose-response pattern of the cytokines IL-6, IL-17A, IL-22, and IL-10. Therefore, results suggest that LPSF/NB-3 appears to modulate important pathways, including cell cycle and immune system regulatory pathways.

Modulatory Effects of Osthole on Lipopolysaccharides-Induced Inflammation in Caco-2 Cell Monolayer and Co-Cultures with THP-1 and THP-1-Derived Macrophages

Lipopolysaccharydes (LPS) are responsible for the intestinal inflammatory reaction, as they may disrupt tight junctions and induce cytokines (CKs) secretion. Osthole has a wide spectrum of pharmacological effects, thus its anti-inflammatory potential in the LPS-treated Caco-2 cell line as well as in Caco-2/THP-1 and Caco-2/macrophages co-cultures was investigated. In brief, Caco-2 cells and co-cultures were incubated with LPS to induce an inflammatory reaction, after which osthole (150-450 ng/mL) was applied to reduce this effect. After 24 h, the level of secreted CKs and changes in gene expression were examined. LPS significantly increased the levels of IL-1β, -6, -8, and TNF-α, while osthole reduced this effect in a concentration-dependent manner, with the most significant decrease when a 450 ng/mL dose was applied (p < 0.0001). A similar trend was observed in changes in gene expression, with the significant osthole efficiency at a concentration of 450 ng/μL for IL1R1 and COX-2 (p < 0.01) and 300 ng/μL for NF-κB (p < 0.001). Osthole increased Caco-2 monolayer permeability, thus if it would ever be considered as a potential drug for minimizing intestinal inflammatory symptoms, its safety should be confirmed in extended in vitro and in vivo studies.

Osthole interacts with an ER-mitochondria axis and facilitates tumor suppression in ovarian cancer

Osthole is a natural coumarin found in a variety of plants and has been reported to have diverse biological functions, including antimicrobial, antiviral, immunomodulatory, and anticancer effects. Here, we investigated the natural derivative osthole as a promising anticancer compound against ovarian cancer and evaluated its ability to suppress and abrogate tumor progression. In addition, we found the endoplasmic reticulum-mitochondrial axis-mediated anticancer mechanisms of osthole against ES2 and OV90 ovarian cancer cells and demonstrated its calcium-dependent pharmacological potential. Mechanistically, osthole was found to target the phosphatidylinositol 3-kinase/mitogen-activated protein kinase signaling pathway to facilitate tumor suppression in ovarian cancer. Furthermore, we identified the effects of osthole in a three-dimensional tumor-formation model using the zebrafish xenograft assay, providing convincing evidence of the pharmacological effects of osthole within the anchorage-independent tumor microenvironment. These findings suggest that osthole has strong potential as a pharmacological agent for targeting ovarian cancer.

Overexpression of ABCB1 and ABCG2 contributes to reduced efficacy of the PI3K/mTOR inhibitor samotolisib (LY3023414) in cancer cell lines

LY3023414 (samotolisib) is a promising new dual inhibitor of phosphoinositide 3-kinase (PI3K) and mammalian target of rapamycin (mTOR). Currently, multiple clinical trials are underway to evaluate the efficacy of LY3023414 in patients with various types of cancer. However, the potential mechanisms underlying acquired resistance to LY3023414 in human cancer cells still remain elusive. In this study, we investigated whether the overexpression of ATP-binding cassette (ABC) drug transporters such as ABCB1 and ABCG2, one of the most common mechanisms for developing multidrug resistance, may potentially reduce the efficacy of LY3023414 in human cancer cells. We demonstrated that the intracellular accumulation of LY3023414 in cancer cells was significantly reduced by the drug efflux function of ABCB1 and ABCG2. Consequently, the cytotoxicity and efficacy of LY3023414 for inhibiting the activation of the PI3K pathway and induction of G0/G1 cell-cycle arrest were substantially reduced in cancer cells overexpressing ABCB1 or ABCG2, which could be restored using tariquidar or Ko143, respectively. Furthermore, stimulatory effect of LY3023414 on the ATPase activity of ABCB1 and ABCG2, as well as in silico molecular docking analysis of LY3023414 binding to the substrate-binding pockets of these transporters provided additional insight into the manner in which LY3023414 interacts with both transporters. In conclusion, we report that LY3023414 is a substrate for ABCB1 and ABCG2 transporters implicating their role in the development of resistance to LY3023414, which can have substantial clinical implications and should be further investigated.

Bufalin reverses multidrug resistance by regulating stemness through the CD133/nuclear factor-κB/MDR1 pathway in colorectal cancer

Recent studies have shown that MDR could be induced by the high stemness of cancer cells. In a previous study, we found bufalin could reverse MDR and inhibit cancer cell stemness in colorectal cancer, but the relationship between them was unclear. Here we identified overexpressing CD133 increases levels of Akt/nuclear factor‐κB signaling mediators and MDR1, while increasing cell chemoresistance. Furthermore, bufalin reverses colorectal cancer MDR by regulating cancer cell stemness through the CD133/nuclear factor‐κB/MDR1 pathway in vitro and in vivo. Taken together, our results suggest that bufalin could be developed as a novel 2‐pronged drug that targets CD133 and MDR1 to eradicate MDR cells and could ultimately be combined with conventional chemotherapeutic agents to improve treatment outcomes for patients with colorectal cancer.

Activity and mechanism of flavokawain A in inhibiting P-glycoprotein expression in paclitaxel resistance of lung cancer

Lung cancer is one of the most common cancers, which is the leading cause of cancer-related death among various cancers worldwide. Flavokawain A (FKA), a chalcone found in the kava plant, exerts potent anticancer activity. However, the activity and mechanisms of FKA in inhibiting the viability of paclitaxel (PTX)-resistant lung cancer A549 (A549/T) have not been investigated. In the present study, the effect of FKA on the viability of A549/T and hepatotoxicity in normal liver epithelial cells was detected by Cell Counting Kit-8 assay. Flow cytometry, western blot analysis and Annexin V-FITC/PI apoptosis detection kit were used to assess cell apoptosis. The effect of FKA on permeability-glycoprotein (P-gp) expression was measured by reverse transcription-PCR and western blot analysis. The results indicated that FKA dose-dependently inhibited cell proliferation and induced cell apoptosis in PTX-resistant A549/T cells, with an IC₅₀ value of ~21 µM, while the IC₅₀ value of A549/T cells to PTX was 34.64 µM. FKA had no hepatic toxicity in liver epithelial cells. P-gp, which contributes to the chemoresistant phenotype, was not expressed in A549 cells but was remarkably enhanced in A549/T cells. FKA (30 µM) decreased P-gp protein expression at 24 h by 3-fold. Furthermore, FKA downregulated P-gp expression by blocking the PI3K/Akt pathway. These findings suggest FKA as a potential candidate for the treatment of PTX-resistant lung cancer.

Translational role of natural coumarins and their derivatives as anticancer agents

Natural coumarins and their derivatives isolated from various plants or microorganisms have inherent antioxidant, antibacterial, antifungal, antiviral and anticancer properties among many biological activities. Some of these coumarins and their derivatives lead to self-programmed cancer cell death (apoptosis) via different mechanisms, which will be discussed. The link between bacterial and viral infections to cancer compels us to highlight fascinating reports from coumarin isolation from microorganisms; comment on the recent bioavailability studies of natural or derived coumarins; and discuss our perspectives with respect to bioisosterism in coumarins, p-glycoprotein inhibition and covalent modification, and bioprobes. Overall, this review hopes to stimulate and offer in particular medicinal chemists and the reader in general an outlook on natural coumarins and their derivatives with potential for cancer therapy.

Osthole inhibits triple negative breast cancer cells by suppressing STAT3

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive subgroup of human breast cancer. Patients with TNBC have poor clinical outcome as they are non-responsive to current targeted therapies. There is an urgent need to identify new therapeutic targets and develop more effective treatment options for TNBC patients. Osthole, a natural product from C. monnieri, has been shown to inhibit certain cancer cells. However, the mechanisms of action as well as its effect on TNBC cells are not currently known.

METHODS

We investigated the effect of osthole in cultured TNBC cells as well as in a xenograft model of TNBC growth. We also used a high-throughput proteomics platform to identify the direct binding protein of osthole.

RESULTS

We found that osthole inhibited the growth of a panel of TNBC cells and induced apoptosis in both cultured cells and TNBC xenografts. We used a high-throughput proteomics platform and identified signal transducer and activator of transcription 3 (STAT3) as a potential binding protein of osthole. We further show that osthole suppressed STAT3 in TNBC cells to inhibit growth and induce apoptosis. Overexpressing STAT3 in TNBC reduced the effectiveness of osthole treatment.

CONCLUSIONS

These results provide support for osthole as a potential new therapeutic agent for the management of TNBC. Moreover, our results indicate that STAT3 may be targeted for the development of novel anti-TNBC drugs.

Antiproliferative effect of ZSTK474 alone or in combination with chemotherapeutic drugs on HL60 and HL60/ADR cells

While chemotherapy remains to be one of the main approaches in the clinical treatment of acute myeloid leukemia (AML), multidrug resistance (MDR) has become a serious problem which limits the therapeutic efficacy. The important roles of the PI3K/Akt pathway in modulating cell proliferation and MDR suggest that PI3K inhibitor might be effective for treatment of AML. In the present study, the antiproliferative effects of PI3K inhibitor ZSTK474 on AML cell HL60 and the adriamycin (ADR)-resistant HL60/ADR cells were investigated. Our data indicated that ZSTK474 exhibited potent antiproliferative activity, induced G1 cell cycle arrest, but no obvious apoptosis in both cell lines. Moreover, ZSTK474 affected the protein levels of cell-cycle-related molecules including increased p27, decreased cyclin D1 and phosphorylated Rb in dose-dependent manner. The proteins downstream of PI3K including phosphorylated PDK1, Akt and GSK-3β were reduced in a dose-dependent manner after ZSTK474 treatment. ZSTK474 reversed ADR resistance, increased the intracellular accumulation of ADR, and reduced the expression and function of multidrug resistance (MDR) proteins including both P-gp and MRP1 in HL60/ADR cells. The combination of ZSTK474 and chemotherapeutic drugs cytarabine or vincristine led to a synergistic effect in HL60 and HL60/ADR cells. In conclusion, ZSTK474 showed potent antiproliferative effect on HL60 and HL60/ADR cells; combination with cytarabine or vincristine resulted in synergistic effect. Our results suggest ZSTK474 has the potential to be applied in the treatment of AML patients, while further evidences particularly those about in vivo efficacy are needed.

Osthole inhibits gastric cancer cell proliferation through regulation of PI3K/AKT

Osthole is an active compound isolated from Chinese herb Cnidium monnieri (L.) Cusson, and had been reported to possess antitumor effect. However, the effect of osthole on the gastric cancer cells has not been investigated. In this study, the effects of osthole on the proliferation of human gastric cancer cells were tested. The data showed that osthole treatment significantly inhibited the proliferation of gastric cancer cells and resulted in the cell cycle arrest at G2/M phase in a dose-dependent manner. Western-blot study showed that the expression of cyclin B1 and cdc2 was markedly reduced by osthole. Moreover, expression of PI3K and pAKT was also significantly suppressed, and the results indicated that the inhibition of pAKT, cyclin B1, and cdc2 levels by osthole was notably enhanced by a PI3K inhibitor. These results demonstrate that osthole could inhibit gastric cancer cells proliferation via induction of cell cycle arrest at G2/M phase by the reduction of PI3K/AKT.

Potential Anticancer Properties of Osthol: A Comprehensive Mechanistic Review

Cancer is caused by uncontrolled cell proliferation which has the potential to occur in different tissues and spread into surrounding and distant tissues. Despite the current advances in the field of anticancer agents, rapidly developing resistance against different chemotherapeutic drugs and significantly higher off-target effects cause millions of deaths every year. Osthol is a natural coumarin isolated from Apiaceaous plants which has demonstrated several pharmacological effects, such as antineoplastic, anti-inflammatory and antioxidant properties. We have attempted to summarize up-to-date information related to pharmacological effects and molecular mechanisms of osthol as a lead compound in managing malignancies. Electronic databases, including PubMed, Cochrane library, ScienceDirect and Scopus were searched for in vitro, in vivo and clinical studies on anticancer effects of osthol. Osthol exerts remarkable anticancer properties by suppressing cancer cell growth and induction of apoptosis. Osthol's protective and therapeutic effects have been observed in different cancers, including ovarian, cervical, colon and prostate cancers as well as chronic myeloid leukemia, lung adenocarcinoma, glioma, hepatocellular, glioblastoma, renal and invasive mammary carcinoma. A large body of evidence demonstrates that osthol regulates apoptosis, proliferation and invasion in different types of malignant cells which are mediated by multiple signal transduction cascades. In this review, we set spotlights on various pathways which are targeted by osthol in different cancers to inhibit cancer development and progression.

miRNA-301a induces apoptosis of chronic myelogenous leukemia cells by directly targeting TIMP2/ERK1/2 and AKT pathways

We investigated the biological functions and mechanism of miRNA‑301a on apoptosis in chronic myelogenous leukemia (CML). The expression of miRNA‑301a in patient with CML cells was higher than the expression of normal patients. Overall survival (OS) of chronic granulocytic leukemia cell patient with low miRNA‑301 expression was superior to that of CML patient with high miRNA‑301 expression. Moreover, the upregulation of miRNA‑301a increased cell proliferation, inhibited apoptosis and caspase-3 and -9 activity of K562 cells. Next, the upregulation of miRNA‑301a suppressed Bax/Bcl-2 rate and TIMP2 protein expression, increased phosphorylation-ERK1/2 and decreased phosphorylation-AKT protein expression of K562 cells. Furthermore, si‑TIMP2 expression enhanced the upregulation of miRNA‑301a on the promotion of cell proliferation, inhibition of apoptosis and caspase-3 and -9 activity, suppression of Bax/Bcl-2 rate, increasing phosphorylation-ERK1/2 and decreasing phosphorylation-AKT protein expression of K562 cells. Taken together, our results clearly suggested that miRNA‑301a induces apoptosis of CML cells by directly targeting the TIMP2/ERK1/2 and AKT pathways.

NSCA-1-a novel N-substituted coumalamide derivative-increases Adriamycin sensitivity in HepG2/adriamycin cells through modulating Akt/GSK-3β signaling and p53-dependant apoptotic pathway

Coumalamide derivatives are one of 2-pyrones derivatives, exerting multifunctional bioactivity. An array of coumalamide derivatives have been developed and presented good antiproliferative properties on cancer cells. However, the synthesis of 5-substituted coumalamide derivatives has not yet been published. Resistance to chemotherapeutic drugs is a major obstacle in hepatocellular carcinoma therapy. Recent evidence suggests that overexpression of constitutively active Akt confers on cancer cells resistance to chemotherapy. In this study, we report the synthesis and biological evaluation of a novel N-substituted coumalamide derivative (NSCA-1). The results indicated that NSCA-1 exerts synergistic cytotoxicity with Adriamycin in HepG2/ADR (HepG2/adriamycin) cells. Furthermore, both of the Akt kinase activity and phosphorylated Akt (Ser473) were found to be inhibited by NSCA-1 and subsequently resulting in decreased phosphorylation of GSK-3β. The intracellular accumulation of Adriamycin was also boosted by NSCA-1 via reducing the expression of p-gp. In addition, we found that combined treatment with NSCA-1 enhance cell apoptosis induced by Adriamycin via p53-dependant apoptotic pathway.

Improving nelarabine efficacy in T cell acute lymphoblastic leukemia by targeting aberrant PI3K/AKT/mTOR signaling pathway

Background

Although in recent years, the introduction of novel chemotherapy protocols has improved the outcome of T cell acute lymphoblastic leukemia (T-ALL) patients, refractory and/or relapsing disease remains a foremost concern. In this context, a major contribution was provided by the introduction of the nucleoside analog nelarabine, approved for salvage treatment of T-ALL patients with refractory/relapsed disease. However, nelarabine could induce a life-threatening, dose-dependent neurotoxicity. To improve nelarabine efficacy, we have analyzed its molecular targets, testing selective inhibitors of such targets in combination with nelarabine.

Methods

The effectiveness of nelarabine as single agent or in combination with PI3K, Bcl2, and MEK inhibitors was evaluated on human T-ALL cell lines and primary T-ALL refractory/relapsed lymphoblasts. The efficacy of signal modulators in terms of cytotoxicity, induction of apoptosis, and changes in gene and protein expression was assessed by flow cytometry, western blotting, and quantitative real-time PCR in T-ALL settings.

Results

Treatment with nelarabine as a single agent identified two groups of T-ALL cell lines, one sensitive and one resistant to the drug. Whereas sensitive T-ALL cells showed a significant increase of apoptosis and a strong down-modulation of PI3K signaling, resistant T-ALL cells showed a hyperactivation of AKT and MEK/ERK1/2 signaling pathways, not caused by differences in the expression of nelarabine transporters or metabolic activators. We then studied the combination of nelarabine with the PI3K inhibitors (both pan and dual γ/δ inhibitors), with the Bcl2 specific inhibitor ABT199, and with the MEK inhibitor trametinib on both T-ALL cell lines and patient samples at relapse, which displayed constitutive activation of PI3K signaling and resistance to nelarabine alone. The combination with the pan PI3K inhibitor ZSTK-474 was the most effective in inhibiting the growth of T-ALL cells and was synergistic in decreasing cell survival and inducing apoptosis in nelarabine-resistant T-ALL cells. The drug combination caused AKT dephosphorylation and a downregulation of Bcl2, while nelarabine alone induced an increase in p-AKT and Bcl2 signaling in the resistant T-ALL cells and relapsed patient samples.

Conclusions

These findings indicate that nelarabine in combination with PI3K inhibitors may be a promising therapeutic strategy for the treatment of T-ALL relapsed patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0344-4) contains supplementary material, which is available to authorized users.

HOXB4 knockdown reverses multidrug resistance of human myelogenous leukemia K562/ADM cells by downregulating P-gp, MRP1 and BCRP expression via PI3K/Akt signaling pathway

Multidrug resistance (MDR) plays a pivotal role in human chronic myelogenous leukemia (CML) chemotherapy failure. MDR is mainly associated with the overexpression of drug efflux transporters of the ATP-binding cassette (ABC) proteins. Phosphoinositide 3-kinase (PI3K)/Akt signaling cascade is involved in the MDR phenotype and is correlated with multidrug resistance 1 (MDR1)/P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1) and breast cancer resistance protein (BCRP) expression in many human malignancies. Homeobox (HOX) B4, a member of the HOX gene family, has been reported to be correlated with occurrence, development, poor prognosis and drug resistance of human leukemia. In the present study, HOXB4 expression was analyzed in K562 cell line and its MDR subline K562/ADM. Compared with K562 cells, drug-resistant K562/ADM cells demonstrated evidently higher HOXB4 expression. In addition, we firstly investigated the reversal effect of HOXB4 deletion on K562/ADM cells and the underlying mechanism. The Cell Counting kit-8 (CCK-8) and flow cytometry assays showed that knockdown of HOXB4 enhanced chemosensitivity and decreased drug efflux in K562/ADM cells. Moreover, HOXB4 knockout led to downregulation of P-gp, MRP1 and BCRP expression and PI3K/Akt signaling activity, suggesting that repression of HOXB4 might be a key point to reverse MDR of K562/ADM cells.